Method and apparatus for forming a batt of particulate material for use as a component in an absorbent core assembly

ABSTRACT

A method and apparatus for forming a batt of particulate material which may be used in an absorbent article. The apparatus may include a vacuum zone, an air impermeable fence zone adjacent to the vacuum zone, and an air permeable fence zone adjacent to the vacuum zone. The air permeable fence zone may comprise an ambient air entry conduit in communication with an ambient air exit port. The method may include providing a laydown drum and a first web of material, positioning the first web of material substantially adjacent to the laydown drum, generating a vacuum through the laydown drum, depositing particulate matter onto the first web of material, and rotating the laydown drum.

FIELD OF THE INVENTION

The present disclosure relates to methods and apparatuses formanufacturing disposable absorbent articles, and more particularly,methods and apparatuses for forming batts of superabsorbent polymer foruse as components in absorbent core assemblies.

BACKGROUND OF THE INVENTION

Disposable absorbent articles, such as diapers, are often constructedwith an absorbent core assembly adapted to absorb bodily exudates andpositioned between layers of materials. Such absorbent core assembliesmay include a mixture of fibrous and particulate materials (e.g., fluffmaterial and superabsorbent polymer), which are formed into a batt orwad. In turn, the batt or wad may be positioned between two or morelayers of materials. One such layer may be a dusting layer adapted toface the wearer's body. Another such layer may be a core wrap adapted toface away from the person's body. The batt may not extend the entirelength of the diaper, and thus, is generally intended to extendlongitudinally inboard of the end edges of the diaper.

In the manufacturing of the absorbent core assemblies, a variety of battforming techniques may be utilized. For example, discrete batts may beformed with the use of vacuum zones within a laydown drum. In someconfigurations, superabsorbent polymer and fluff material are depositedonto a web partially wrapped around the outer surface of the laydowndrum. Vacuum zones on the outer surface of the laydown drum help placeand hold the superabsorbent polymer and fluff material in desiredlocations on the web. However, using some current techniques andapparatuses, some superabsorbent polymer and fluff material may beinadvertently deposited outside of the vacuum zones and outside desiredlocations on the web. For example, in some instances, superabsorbentpolymer may be deposited substantially along the entire length of thediaper. As a result, the superabsorbent polymer may subsequently migratethrough the topsheet, causing the superabsorbent polymer to be depositedon the wearer's skin. Such deposits may cause skin irritation; may bebelieved to cause skin irritation; and/or may be aestheticallyunacceptable to a consumer. Additionally, fluff material inadvertentlydeposited substantially along the entire length of the diaper mayinterfere with an end seal necessary to contain the absorbent coreassembly.

In response to the aforementioned problems, some laydown drums may beconfigured with additional systems to help prevent the superabsorbentpolymer and fluff mate from migrating outside the vacuum zones. Forexample, some laydown drums may include pneumatic systems that forcecompressed air through zones in the laydown drum to help prevent thedeposit of particulate material along the entire length of the diaper.However, such systems add cost and complexity to the manufacturingprocess.

Thus, there remains a need for simplified methods and apparatuses forforming batts comprising particulate material (e.g., fluff material andsuperabsorbent polymer) for use as a component in an absorbent coreassembly.

SUMMARY OF THE INVENTION

In some embodiments, the present disclosure is directed to an apparatusfor forming a batt comprising particulate material, the apparatuscomprising a support structure having an outer surface, a plurality ofvacuum zones disposed on the outer surface of the support structure, atleast one air impermeable fence zone adjacent to each vacuum zone, andat least one air permeable fence zone adjacent to each vacuum zone. Theair permeable fence zone may comprise an ambient air entry conduit influid communication with an ambient air exit port. A vacuum appliedbeneath the vacuum zones may draw ambient air into the ambient air entryconduit and radially outward from the ambient air exit port. In someembodiments, the support structure may be a laydown drum.

In some embodiments, the ambient air entry conduit does not extendthrough the surface of the laydown drum. A collective surface area ofvacuum zones, air permeable fence zones, and air impermeable fence zonesmay equal a surface area of the outer surface of the laydown drum. Theambient air entry conduits may comprise fins at one or more laterallyoutermost edges of the ambient air entry conduits, whereby the finsdirect ambient air into the ambient air entry conduit when the laydowndrum is rotated. The vacuum zones may comprise a screen having aplurality of apertures.

The air impermeable fence zones and the air permeable fence zones mayhave a greater height relative to the outer surface of the supportstructure than the vacuum zones. The air impermeable fence zones and theair permeable fence zones may be less than about 7 mm higher than thevacuum zones relative to the outer surface of the support structure.

In some embodiments, the disclosure relates to a method of forming abatt comprising particulate material, the method comprising the steps ofproviding a support structure, the support structure having an outersurface and a plurality of vacuum zones, the vacuum zones beingsubstantially permeable to permit vacuum air to pass through and intothe laydown drum, a plurality of air impermeable fence zones, the airimpermeable fence zones being substantially impermeable to inhibit airto pass through, the air impermeable fence zones being positionedlaterally adjacent the vacuum zones on the outer surface of the supportstructure, and a plurality of air permeable fence zones, the airpermeable fence zones comprising an ambient air entry conduit incommunication with an ambient air exit port, the air permeable fencezones being substantially permeable to permit ambient air to passthrough the air permeable fence zones, the air permeable fence zonesbeing positioned between the vacuum zones on the surface of the supportstructure, generating a vacuum through the laydown drum such that air isdrawn through the vacuum zones and the air permeable fence zones, anddepositing a dispersion comprising air and particulate material suchthat the vacuum applied to the vacuum zones directs the dispersion tothe vacuum zones whereupon the particulate material is positioned toform a batt.

The method may further comprise providing a web of substrate material,pulling the web of substrate material substantially adjacent to thevacuum zones, and depositing the dispersion of air and particulatematerial on the web in the vacuum zones. In some embodiments, the methodmay include severing the first web to form a plurality of discretebatts. The method may further comprise the steps of providing a secondweb of material, positioning the second web of material adjacent theparticulate material, and combining the second web of material to thefirst web of material. The combined webs may be severed to form aplurality of discrete batts.

The first and second webs may be combined prior to severing the web toform the plurality of batts. The particulate material may comprisesuperabsorbent polymer particles. The superabsorbent polymer particlesmay be shielded after they are deposited. The first and second web ofmaterials may be bonded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a series of absorbent articles made from a plurality ofweb materials.

FIG. 1B shows an exemplary absorbent article.

FIG. 2A shows the absorbent core assembly from FIG. 1A.

FIG. 2B shows a cross-sectional view of the absorbent core assembly fromFIG. 2A taken along line 2B-2B.

FIG. 3 shows a schematic representation of an exemplary manufacturingprocess for forming absorbent core assemblies.

FIG. 4A shows a cross-sectional view of a laydown drum.

FIG. 4B is an isometric view of a laydown drum.

FIG. 4C shows a detailed perspective view of vacuum and fence zones onthe laydown drum of FIG. 4A.

FIG. 4D shows a detailed perspective view of an air permeable fence zonefrom FIG. 4C.

FIG. 4E shows exemplary vacuum and fence zones.

FIG. 4F shows air permeable fence zones having fins.

FIG. 5 shows a laid-out view of the surface of laydown drum from FIG.4B.

FIG. 6A shows a dusting layer having a central adhesive applied in astriped pattern.

FIG. 6B shows a vacuum-formed outline of a mixture of fluff material andSAP.

FIG. 6C shows an underlying layer of core wrap material with a pluralityof adhesive application patterns.

FIG. 7 shows an SAP shield adjacent the fluff material deposition chuteof FIG. 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following term explanations may be useful in understanding thepresent disclosure.

The term “absorbent article” herein refers to devices which absorb andcontain body exudates and, more specifically, refers to devices whichare placed against or in proximity to the body of the wearer to absorband contain the various exudates discharged from the body, such as:incontinence briefs, incontinence undergarments, absorbent inserts,diaper holders and liners, feminine hygiene garments and the like. Theabsorbent article may have an absorbent core having a garment-facingsurface and a body-facing surface when fitted to a wearer, a liquidpermeable topsheet positioned adjacent the body-facing surface of theabsorbent core, and a liquid impermeable backsheet positioned adjacentthe garment-facing surface of the absorbent core.

The term “air permeable” is used herein to describe a surface whichpresents little or no resistance to air flow through the surface.Examples include screens, meshes, holes, and open areas. A surface whichis air permeable in itself may present increased resistance to air flowas materials, such as nonwoven webs, fibers, or particulates, aredeposited on the surface. Air permeable screens may be perforatedmaterials defined by their thickness, hole size, and open area.Exemplary screens may have a thickness from about 0.125 mm to about 0.5mm, for example 0.254 mm, with hole diameters from about 0.254 mm toabout 3 mm, for example 1.0 mm, and open areas from about 30% to about70%. Said air permeable screens may have Darcy Porosity values fromabout 0.30 to about 0.70 where porosity n=V_(v)/V_(t) and V_(v)=VoidVolume and V_(t)=Total Volume. Air permeable screens may also be definedby Darcy Void Ratio such screens having a void ratio from about 0.43 toabout 2.3, for example having a void ratio of 0.75, where the void ratioe=V_(v)/V_(s) and V_(v)=Void Volume and V_(s)=Solid Volume. Airpermeable surfaces that are wire screens may be defined by wirediameter, width of opening between wires, and open area. Such wirescreens may have wire diameters from about 0.114 mm to about 1.19 mm,for example 0.457 mm in diameter; they may have opening widths betweenwires from about 0.14 mm to about 3.05 mm, for example 1.13 mm; they mayhave overall open areas from about 30.3% to about 51.8%, for example50.7%. Screen Mesh may also be used to define the air permeability ofthe surface and may range for 6 Mesh to 100 Mesh most preferably 16Mesh, where Mesh=1/(D+O) and D=Wire Diameter and O=Opening betweenwires.

The term “air impermeable” is used herein to describe a surface whichpresents significant resistance to air flow through the surface,effectively allowing zero air flow through the surface when subjected toa negative pressure equal to or less than minus 0.122 atmospheres ornegative 50 inches of water.

The term “disposable” is used herein to describe absorbent articleswhich generally are not intended to be laundered or otherwise restoredor reused as absorbent articles (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise discarded in an environmentally compatible manner).

The term “diaper” herein refers to an absorbent article generally wornby infants and incontinent persons about the lower torso to receive andcontain excreta.

The term “longitudinal” herein refers to a direction running parallel tothe maximum linear dimension of the article and includes directionswithin ±45° of the longitudinal direction.

The term “lateral” herein refers to a direction which is perpendicularto the longitudinal direction.

The term “fluff material” refers to any material suitable for suspendingand/or entangling with superabsorbent polymer. Fluff material may bemade of a variety of materials including, but not limited to, syntheticfibers having a length suitable for airlaying, cellulose fibersincluding cross-linked cellulose fibers, or the like, and combinationsthereof.

The term “substantially adjacent” herein refers to two or more itemspositioned so that they are lying near or close to one another, or sothat they are touching at one side or surface. Substantially adjacentitems may be adjacent over only a portion of their side or surface. Forexample, placing a continuous web material substantially adjacent to adrum may involve adjacency between only a portion of the continuous webmaterial and a portion of the drum's surface.

The term “superabsorbent polymer” herein refers to a polymer which iscapable of absorbing within the polymer at least 10 times its weight indeionized water. Superabsorbent polymer may be made of a variety ofmaterials including, but not limited to, polyacrylic acid, sodiumpolyacrylate, polyacrylamide, polyacrylonitrile, polyvinyl alcohol,maleic anhydride, a polyether, a condensed polymer, a polysaccharidesuch as starch or cellulose, a protein such as collagen, or the like,and combinations thereof. Examples of the superabsorbent polymersinclude: a cross-linked compound of sodium polyacrylate, a graftcopolymer of starch having sodium polyacrylate, or a graft copolymer ofcellulose having polyacrylonitrile chains.

The present disclosure relates to apparatuses and methods formanufacturing absorbent core assemblies for disposable absorbentproducts, and in particular, for forming batts comprising particulatematerial used in absorbent core assemblies. In particular, the methodsand apparatuses herein are configured to channel air through a conduitto help direct the particulate material to desired locations duringmanufacture. For example, some embodiments include a rotating laydowndrum having an outer surface with defined vacuum zones and fence zones.In one embodiment, a vacuum system in fluid communication with thelaydown drum may draw air from outside the laydown drum through thevacuum zones and into the laydown drum. As discussed in more detailbelow, the vacuum applied to the vacuum zones may also be used to drawair through a conduit on the surface of the laydown drum and through theair permeable fence zones. During the manufacture of absorbent coreassemblies, particulate material is deposited onto a web of materialwhile the web is substantially adjacent to the outer surface of thelaydown drum. As the particulate material is deposited onto the web, airtraveling through the vacuum zones into the laydown drum helps direct,place, and hold the particulate material in desired positions on theweb. At the same time, air pulled through the air permeable fence zonesmoves generally away from the laydown drum as it first exits the airpermeable fence zones, and helps prevent particulate material from beingdeposited on the web outside of desired locations.

The present disclosure further relates to the formation of a battcomprising particulate material without the immediate use of a webmaterial. A laydown drum having vacuum zones and air permeable fencezones as described above can be used to form a batt comprisingparticulate material on a mesh or screen disposed in the vacuum zone.The batt can then be transferred to a supporting material, such as a webor a partially formed absorbent article. Throughout this description, alaydown drum is referenced as the subjacent support for the vacuumzones, air permeable fences, and air impermeable fences. However, avariety of subjacent support structures would be acceptable. Forexample, it would be possible to adapt the embodiments of the disclosureto use, instead of a laydown drum, a conveyor belt, another movingsurface, or even to configure a fixed support structure.

The following provides a description of a basic diaper construction withreference to accompanying figures to help illustrate the apparatuses andmethods described below. As such, it is to be appreciated that otherdiaper constructions can be utilized with the methods and apparatusesherein. Although the present disclosure is provided in the context ofmanufacturing diapers, it is to be appreciated that the apparatuses andmethods herein may be applied to the manufacture of various types ofabsorbent articles.

During the manufacture of absorbent articles, substrates may be combinedwith the other substrates and/or discrete components to create acontinuous length of absorbent articles. At a downstream portion of themanufacturing process, the continuous length of absorbent articles issubjected to a final knife cut to create separate and discrete absorbentarticles. FIG. 1A shows a portion of a continuous length of absorbentarticles made from a combination of web and component materials. Inparticular, FIG. 1A shows a first absorbent article 100 a, a secondabsorbent article 100 b and a third absorbent article 100 c in anend-to-end configuration, as might exist prior to a final knife cutwithin a manufacturing process. FIG. 1B shows a discrete absorbentarticle in the form of a diaper. The absorbent article 100 includes atopsheet 110, a backsheet 120 and an absorbent core assembly 130containing a batt 150 of particulate material. The absorbent coreassembly 130 of FIG. 1B is shown in detail in FIGS. 2A and 2B. Absorbentcore assembly 130 may comprise dusting layer 132, core wrap layer 134,and a mixture of fibrous and particulate material, for example fluffmaterial 136 and superabsorbent polymer (hereinafter SAP) 138,positioned between dusting layer 132 and core wrap layer 134 and formingbatt 150. As shown in FIG. 2B, dusting layer 132 may be positioned onone side of batt 150 and core wrap layer 134 may be positioned oppositedusting layer 132; however, a variety of other configurations arepossible.

Absorbent core assemblies, and in particular, batts, may be formed bydepositing material, including particulate material, onto a web orsubstrate advancing along a rotating laydown drum. FIG. 3 shows anexemplary manufacturing process 1000 for forming a batt wherein materialincluding particulate material is deposited onto a continuous web ofdusting layer material 132 advancing through the process. Process 1000may utilize various mechanisms and a variety of other web handlingdevices, such as laydown drum 1060, SAP applicator 1138, or fluffmaterial deposition chute 1136. Central adhesive applicator 1142 mayapply adhesive to at least one side of the dusting layer. While avariety of adhesive application patterns may be used, one such patternis depicted later in FIG. 6A. After the central adhesive is applied,dusting layer 132 may be fed to an underneath position in relationshipto fluff material deposition chute 1136. Throughout this manufacturingprocess, a variety of web handling devices may be used including, butnot limited to, idler rollers 1052, 1054, 1056, 1058. Next, batt 150 maybe formed by SAP 138 and fluff material 136 being applied to the top ofdusting layer 132 with the aid of air being drawn by vacuum through andinto the interior of laydown drum 1060. As discussed in more detailbelow, laydown drum 1060 may include multiple zones to help deposit andmaintain the SAP and fluff material in desired locations on the dustinglayer, such as vacuum zones 1062, air impermeable fence zones 1064 andair permeable fence zones 1066.

It is also possible to form batt 150 using process 1000 without dustinglayer 132. In such an embodiment, the substrate may be part of laydowndrum 1060. For example, the substrate may be a screen disposed in vacuumzones 1062 to hold SAP 138 and fluff material 136. In someconfigurations, the screen is made of metal for durability, but it maybe made of any suitable material which will permit air to pass throughthe screen under the influence of a vacuum and will retain SAP 138 andfluff material 136 to form batt 150. In some embodiments, the metalscreen may have a plurality of small apertures, each having a diameterof approximately 0.011 inches (approximately 0.028 cm). It will beappreciated that the shape, configuration, material, and size of thescreen and the apertures may be adjusted depending upon the specificset-up of process 1000, including the magnitude of the vacuum used, thesize and quantity of particles distributed to each batt 150, and thedesired shape and thickness of batt 150. Once formed, batt 150 may thenbe transferred from the screen on the surface of laydown drum 1060 toany desired carrier, such as dusting layer 132 or an alternatesubstrate.

In parallel with the processes described above, a web of core wrapmaterial 134 may also be fed into the process in a direction relativelytowards the fluff material deposition chute 1136. Adhesive may beapplied to the core wrap, for example, by side adhesive applicator 1144,end adhesive applicator 1146, and auxiliary adhesive applicator 1148.While a variety of adhesive application patterns may be used, one suchcollection of patterns is depicted in FIG. 6C and discussed below. Afterthe adhesive is applied, the core wrap material may be brought intocontact with dusting layer 132 and batt 150 formed by the mixture of SAP138 and fluff material 136. Next, the webs of materials may be bonded.For example, phased bonding roll 1070 may be used to provideintermittent bonding so as to bond the layers of materials betweendiscrete batts 150 formed by the depositions of SAP and fluff material.

As mentioned above, the laydown drum includes vacuum and fence zonesconfigured to maintain the particulate material deposited on the web indesired locations. As shown in FIGS. 4A and 4B, the surface of laydowndrum 1060 may include at least two distinct zones, namely, a pluralityof vacuum zones 1062 and a plurality of air permeable fence zones 1066.Also shown in FIG. 4A is fluff material deposition chute 1136 whereinSAP 138 and fluff material 136 are dispersed and mixed in air to form anair/particulate dispersion. It is from fluff material deposition chute1136 that SAP 138 and fluff material 136 are deposited to form the batts150. By way of pulling air 1063 through vacuum zones 1062, theair/particulate dispersion is directed to the vacuum zones whereupon SAP138 and fluff material 136 are positioned to form discrete batts 150 ofabsorbent core material. With the additional use of ambient air flow1067 through air permeable fence zones 1066, the formation of discretebatts is improved such that the amount of loose particles of SAP 138and/or fluff 136 material inadvertently positioned within the spacebetween the batts is minimized.

As shown in FIG. 4C, an air permeable fence zone 1066 may be located ateach longitudinal end of vacuum zone 1062. Air flow through the vacuumzone 1063 is driven by a vacuum fan or pump (not shown), which pulls airinto the laydown drum. Air flow through the air permeable fence zones1067 is drawn by the vacuum applied to the vacuum zones, and extendsgenerally perpendicular to the laydown drum (not shown) at the surfaceof the laydown drum, over the air permeable fence, and eventuallythrough the vacuum zone into the laydown drum. The air flow through theair permeable fence zones 1067 begins at the ambient air entry conduit1070, and continues out the ambient air exit ports 1072. An individualvacuum zone 1062 may also be laterally adjacent to air impermeable fencezones 1064.

As shown in FIG. 4D, ambient air is drawn into the ambient air entryconduit 1070 of air permeable fence zone 1066 and flows through ambientair exit ports 1072. Unlike vacuum zone 1062, through which air flowsinto laydown drum 1060, the ambient air entry conduit 1070 may bedisposed on the surface of the laydown drum. That is, the air permeablefence zones may be configured such that air entry conduit 1070 do notextend below the surface of laydown drum 1060. The embodiment depictedin FIG. 4D shows an air permeable fence zone 1066 having a squarecross-section, air entry conduit 1070, and a plurality of air exit ports1072. The air permeable fence zone 1066 may have any of a multitude ofalternate cross-sectional shapes, such as triangles, circles, ovals,parallelograms, etc., and the cross-sectional shape or size may varyover the length of the air permeable fence zone 1066. The air permeablefence zone 1066 may also have one air entry conduit 1070 or a pluralityof air entry conduits 1070, and one or several distinct air exit ports1072. The sides and bottom of air entry conduits 1070 may be airimpermeable to facilitate air flow through air exit ports 1072. Theamount, force, and direction of the air flow through the air permeablefence zones 1066 can be modified by varying the configurations of airentry conduits 1070 and air exit ports 1072. In some embodiments, theends of air exit ports 1072 may include fins 1100, as shown in FIG. 4F,such that ambient air is directed through air permeable fence zones 1066by the rotation of laydown drum 1060.

Vacuum zone 1062 is recessed relative to air impermeable fence zones1064, as shown in FIG. 4E. The height of air impermeable fence zones1064 relative to vacuum zone 1062 may vary depending upon the desiredthickness of batt 150, and the particulars of manufacturing process1000. If a web is used as a substrate moving over the surface of laydowndrum 1060 to receive batt 150, the height of air impermeable fence zones1064 may be limited by the minimum acceptable edge definition of batt150. In some instances, the vacuum applied to vacuum zones 1062 may pullthe web closely against the edges of vacuum zone 1062 and the fencezones, allowing SAP 138 and fluff material 136 to form distinct, evenedges having the shape of the vacuum zone. If the height of airimpermeable fence zones 1064 is too great, the web may not conform tothe edges of vacuum zone 1062, and SAP 138 and fluff material 136 maynot be distributed evenly where the web is bowed. Thus, if the height ofair impermeable fence zones 1064 is too great, batts 150 may haveindistinct, uneven edges which are functionally or aestheticallyunacceptable. In some configurations, the maximum air impermeable fenceheight suitable for use with a web or other substrate is approximately5-7 mm. The height of air permeable fence zones 1066 may also be limitedby similar concerns, although it is not necessary that the height of airpermeable fence zones 1066 match each other or the height of airimpermeable fence zones 1064.

FIG. 5 shows a laid-out view of the surface of laydown drum 1060 fromFIG. 4. In the embodiment shown, vacuum zones 1062 have an hourglassshape, however, vacuum zones 1062 can have nearly any shape to form thedesired outline of discrete batts 150. Vacuum zones 1062 aresubstantially air-permeable to allow air to pass through. In contrast,air impermeable fence zones 1064 may be used to inhibit air flow andthus inhibit the placement of SAP/fluff material in the locations of airimpermeable fence zones 1064. Air impermeable fence zones 1064 need notbe completely air impermeable, so long as they are sufficiently airimpermeable to inhibit air to pass through under vacuum. In someembodiments, the air impermeable fence zones may be laterally adjacentto the vacuum zones as shown in FIG. 5.

The air flow generated by the vacuum under the vacuum zones pulls airthrough air permeable fence zones 1066. Air flow 1067 through airpermeable fence zones 1066 may, at least initially, be generally awayfrom the surface of laydown drum 1060, or radially outward from thesurface of the laydown drum, as shown in FIGS. 4C and 4D. Thus, air flow1067 through air permeable fence zones 1066 limits the placement ofSAP/fluff material in these locations by blowing away any SAP/fluffmaterial inadvertently deposited in the vicinity of air permeable fencezones 1066. The use of air permeable fence zones 1066 in the areabetween the vacuum zones helps reduce the amount of deposited SAP/fluffmaterial which would ultimately be positioned within the waist region ofthe resulting absorbent article. Having SAP positioned in the waistregion may be undesirable, for example, because the SAP particles arenot constrained by fluff material or the core cover of the absorbentcore, thus the SAP particles may have a greater tendency to migratethrough the top sheet and come in contact with the wearer. Particulatedeposits in the waist region of the absorbent article may also interferewith bonding, such as adhesive bonding or mechanical bonding, in thatregion. The use of ambient air in air permeable fence zones 1066 meansthat no additional equipment or power input is necessary to produceforced air to blow SAP particles away from the spaces between the batts.

FIG. 6A shows dusting layer 132 having central adhesive 142 applied in astriped pattern. FIG. 6B shows the vacuum-formed outline of batt 150containing a mixture of fluff material 136 and SAP 138. While anhour-glass shape is shown, other shapes may be used. FIG. 6C shows anunderlying layer of core wrap material 134 with a plurality of adhesiveapplication patterns, namely, side adhesive 144 and end adhesive 146applied to the perimeter of the core wrap. Additionally, auxiliaryadhesive 148 may be applied in the field within the side and endadhesives. The use of adhesives helps to form a laminate of the dustinglayer, the batt containing fluff material/SAP, and the core wrap. Whilea striped pattern is shown in FIGS. 6A and 6C, various other adhesiveapplication patterns may be used.

FIG. 7 shows the addition of SAP shield 1137 which may be attached tofluff material deposition chute 1136 so as to extend the amount ofcoverage around the laydown drum 1060 and thus help minimize the amountof SAP particles which might otherwise bounce off of the laydown drumand away from the web. While particulate material comprising SAP andfluff material was discussed above, it is also possible to use only SAP,or substantially only SAP, or substantially only fluff material. Forexample, the particulate material may include greater than 90% SAP, orgreater than 95% SAP, or even greater than 98% SAP. The particulatematerial may also comprise adhesive. The adhesive may be mixed with theparticulate material prior to deposition, or the adhesive may be appliedbefore, during, or after the deposition of the particulate material.

Various known processes for producing absorbent core particulate battscould be modified to include the air permeable fence zones disclosedherein. For example, air permeable fence zones could be incorporatedinto the processes described in U.S. Patent Application No. 61/091,799by Hundorf, et al., filed Aug. 26, 2008; and in International PatentApplication Publication No. WO 2008/117109 A1 by Bianco, et al., filedDec. 3, 2007; or in virtually any other core forming process.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or incombination with any other reference or references, teaches, suggests,or discloses any such invention. Further, to the extent that any meaningor definition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. An apparatus for forming a batt comprising particulate material, theapparatus comprising: a support structure having an outer surface; aplurality of vacuum zones disposed on the outer surface of the supportstructure; at least one air impermeable fence zone adjacent to eachvacuum zone; and at least one air permeable fence zone adjacent to eachvacuum zone, the air permeable fence zone comprising an ambient airentry conduit in fluid communication with an ambient air exit port;wherein a vacuum applied beneath the vacuum zones draws ambient air intothe ambient air entry conduit and radially outward from the ambient airexit port.
 2. The apparatus of claim 1, wherein the support structure isa laydown drum.
 3. The apparatus of claim 2, wherein the ambient airentry conduit does not extend through the surface of the laydown drum.4. The apparatus of claim 2, wherein a collective surface area of vacuumzones, air permeable fence zones, and air impermeable fence zones equalsa surface area of the outer surface of the laydown drum.
 5. Theapparatus of claim 2, wherein the ambient air entry conduits comprisefins at one or more laterally outermost edges of the ambient air entryconduits, whereby the fins direct ambient air into the ambient air entryconduit when the laydown drum is rotated.
 6. The apparatus of claim 1,wherein the vacuum zones comprise a screen having a plurality ofapertures.
 7. The apparatus of claim 1, wherein the air impermeablefence zones and the air permeable fence zones have a greater heightrelative to the outer surface of the support structure than the vacuumzones.
 8. The apparatus of claim 7, wherein the air impermeable fencezones and the air permeable fence zones are less than about 7 mm higherthan the vacuum zones relative to the outer surface of the supportstructure.
 9. A method of forming a batt comprising particulatematerial, the method comprising the steps of: providing a supportstructure, the support structure having an outer surface and a pluralityof vacuum zones, the vacuum zones being substantially permeable topermit vacuum air to pass through and into the support structure; aplurality of air impermeable fence zones, the air impermeable fencezones being substantially impermeable to inhibit air to pass through,the air impermeable fence zones being positioned laterally adjacent thevacuum zones on the outer surface of the support structure; and aplurality of air permeable fence zones, the air permeable fence zonescomprising an ambient air entry conduit in communication with an ambientair exit port, the air permeable fence zones being substantiallypermeable to permit ambient air to pass through the air permeable fencezones, the air permeable fence zones being positioned between the vacuumzones on the surface of the support structure; generating a vacuumthrough the laydown drum such that air is drawn through the vacuum zonesand the air permeable fence zones; and depositing a dispersioncomprising air and particulate material such that the vacuum applied tothe vacuum zones directs the dispersion to the vacuum zones whereuponthe particulate material is positioned to form a batt.
 10. The method ofclaim 9 further comprising: providing a first web of substrate material;pulling the web of substrate material substantially adjacent to thevacuum zones; and depositing the dispersion of air and particulatematerial on the web in the vacuum zones.
 11. The method of claim 10further comprising the step of severing the first web to form aplurality of discrete batts.
 12. The method of claim 10 furthercomprising the steps of: providing a second web of material; positioningthe second web of material adjacent the particulate material; andcombining the second web of material to the first web of material. 13.The method of claim 12 further comprising the step of severing thecombined webs to form a plurality of discrete batts.
 14. The method ofclaim 13, wherein the first and second webs of material are combinedprior to severing the web to form the plurality of discrete batts. 15.The method of claim 9, wherein the particulate material comprisessuperabsorbent polymer particles.
 16. The method of claim 9, furthercomprising the step of shielding the particulate material as theparticulate material is deposited.
 17. The method of claim 12, furthercomprising the step of bonding the first and second webs of materials.